Chem 101 practice final exam - Cal State LA

1 Chem 101 General Chemistry practice final Exam Name _____ h = x 10-34 J s (Planck s Constant) c = x 108 m/s (speed of light) RH = x 10-7 m-1 (Rydberg Constant) Multiple Choice (5 points each) Identify the letter of the choice that best completes the statement or answers the question and legibly write the letter in the space preceding the problem number. ____ 1. Which of the following is not a solution? a. red wine b. alcohol in water c. brass d. air e. ice in water ____ 2. Which of the following statements concerning the atom is false? a. Chemical reactions involve only the electrons. b. The atom contains protons, neutrons and electrons. c. Protons are found in orbits about the nucleus. d. The nucleus contains both protons and neutrons. e. Most of the mass of the atom is found in the nucleus. ____ 3. Which of the following statements about two isotopes is false?

2 A. They will have the same charge on the nucleus. b. They will have different numbers of neutrons. c. They will have essentially the same chemical reactivity. d. They will have the same atomic numbers. e. They will have the same atomic weights. ____ 4. Which element can be classified as an alkaline earth metal? a. Al b. Mg c. Ag d. Au e. Na ____ 5. Which combination below corresponds to a cation with a +1 charge? a. 7 protons and 8 electrons b. 11 protons and 10 electrons c. 18 protons and 18 electrons d. 17 protons and 18 electrons e. 20 protons and 18 electrons ____ 6. When g of pure iron is allowed to react with an excess of oxygen, g of the final compound is produced. Determine the formula of the compound. a. Fe2O3 b. FeO c. FeO2 d. FeO3 e. FeO4 ____ 7. The complete combustion of a hydrocarbon produces g of CO2 and g of H2O.

3 What is the empirical formula of the hydrocarbon? a. CH b. CH2 c. C2H5 d. C3H8 e. C3H4 ____ 8. Ammonia and sulfuric acid react according to the equation given below. How many milliliters of M sulfuric acid are required to exactly neutralize mL of M NH3 solution? 2 NH3(aq) + H2SO4(aq) (NH4)2SO4(aq) a. mL b. mL c. mL d. mL e. mL ____ 9. Determine if each of the four situations below describes kinetic or potential energy. I a moving bullet II picture hanging on a wall III the bonds in a mixture of H 2 and O2 IV the movement of molecules I II III IV a. potential kinetic kinetic potential b. potential potential kinetic kinetic c. kinetic potential kinetic potential d. kinetic kinetic potential potential e.

4 Kinetic potential potential kinetic ____ 10. What is the molar heat capacity of table salt, NaCl (specific heat = J g-1 C-1)? a. 1022 J mol-1 C-1 b. J mol-1 C-1 c. J mol-1 C-1 d. 117 J mol-1 C-1 e. 245 J mol-1 C-1 ____ 11. A sample of water containing moles is initially at C. If the sample absorbs kJ of heat, what is the final temperature of the water? (specific heat of water = J g-1 C-1) a. C b. C c. C d. C e. 269 C ____ 12. What is the enthalpy change when 225 g of C2H2 are burned in excess O2? C2H2(g) + 5/2O2(g) 2CO2(g) + H2O(l) H = -1300 kJ a. 104 kJ b. 104 kJ c. 105 kJ d. + 104 kJ e. + 105 kJ ____ 13. Determine the heat of reaction for the process TiO2(s) + 4 HCl(g) TiCl4(l) + 2H2(g) + O2(g) using the information given below: Ti(s) + O2(g) TiO2(s) H = kJ 2 HCl(g) H2(g) + Cl2(g) H = kJ Ti(s) + 2Cl2(g) TiCl4(l) H = kJ a.

5 KJ b. kJ c. kJ d. kJ e. kJ ____ 14. Which of the following is not a characteristic of the Bohr model of the atom? a. An electron is located in an orbit around the nucleus. b. Each orbit has a discrete energy associated with it. c. Orbits have defined radii. d. There is a continuum of energy levels that an electron can have around a nucleus. e. Orbits have a defined circumference. ____ 15. Which azimuthal quantum numbers can exist for n = 3? a. l = 0 b. l = 0, 1 c. l = 0, 1, 2 d. l = 0, 1, 2, 3 e. l = 0, 1, 2, 3, 4 ____ 16. If l = 1, what value can ml have? a. ml = -1 b. ml = +1 c. ml = 0, +1 d. ml = 0 e. ml = -1, 0, +1 ____ 17. How many electrons can the second principal quantum level hold? a. 2 b. 8 c. 16 d. 18 e. 32 ____ 18. Which of the following has the electron configuration 1s22s22p63s23p6? a.

6 Ca b. Cl c. Ar d. K+ e. Both c and d ____ 19. Which element has the largest atomic radius? a. F b. He c. O d. H e. Na ____ 20. Which element will have five electrons in its Lewis symbol? a. beryllium b. neon c. oxygen d. carbon e. nitrogen ____ 21. Which molecule does not contain a double bond? a. CO2 b. CH2O c. O2 d. HCOOH e. HCN ____ 22. Write the correct Lewis dot structure for CO. Which statement correctly describes the structure? a. The structure contains 1 single bond and 6 lone pairs. b. The structure contains 1 single bond and 7 lone pairs. c. The structure contains 1 double bond and 4 lone pairs. d. The structure contains 1 double bond and 5 lone pairs. e. The structure contains 1 triple bond and 2 lone pairs. ____ 23. Write the correct Lewis dot structures for the compounds given below. Arrange them in order of shortest to longest bond lengths.

7 Consider only the carbon-carbon and carbon-oxygen bonds. C2H2 C2H6 C2H4 CO a. C2H6 < C2H4 < C2H2 < CO b. C2H2 < CO < C2H4 < C2H6 c. C2H2 < C2H4 < C2H6 < CO d. CO < C2H2 < C2H4 < C2H6 e. CO < C2H6 < C2H4 < C2H2 ____ 24. From the data given below, calculate the approximate enthalpy change of reaction for the reaction below. CH4(g) + 2O2(g) CO2(g) + 2H2O(g) bond enthalpy kJ/mol C-H 414 C-C 347 C=C 611 C-O 351 C=O 803 O-H 463 O=O 498 H-H 436 a. -806 kJ b. -98 kJ c. 98 kJ d. 120 kJ e. 806 kJ ____ 25. Which statement properly describes the formal charges on the atoms in ? a. +2 on sulfur, -2 on oxygen b. +2 on sulfur, -1 on oxygen c. +1 on sulfur, -1 on oxygen d. -1 on sulfur, +2 on oxygen e. -2 on sulfur, 0 on oxygen 26. (15 points) Which species has a greater ionization energy: Ne or Na+?

8 Explain why. 27. (15 points) List the following atoms in the correct order of increasing (smallest to largest) atomic radii: Bromine (Br), Fluorine (F), Sulfur (S), Arsenic (As) 28. (15 points) Draw the Lewis structure of carbonic acid, H2CO3, and determine the formal charge of each atom in the structure. 29. (15 points) Draw the molecular orbital energy diagram for nitrogen monoxide, NO, and determine the bond order of the molecule. (Reminder: place the atomic orbitals at appropriate relative energies based on the electronegativity of the nitrogen and oxygen.) 30. (15 points) Iodine (I2) is a solid at room temperature but sublimes easily Hosub = kJ/mol. If g of I2(s) is irradiated with 510 nm light, how many photons are required to vaporize this amount of iodine?